Don't use this. It is ancient. Use https://github.com/ev1313/Pascal-SDL-2-Headers instead.
You need at least FreePascal 2.2.* or Delphi 7.
Triple-licensed (MIT, MPL, zlib)
Why?
MIT: My personal favorite license
MPL: To be fully compatible JEDI-SDL (SDL 1.2 headers)
zlib: To be fully compatible with SDL 1.3's license